<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div
        {
            /* font-weight: bolder; */
            font-weight: lighter;
            /* font-weight: 700px; */
        }

    </style>
</head>
<body>
    <h3>3.字体粗细</h3>
    <div>
        字体粗细设置
    </div>
</body>
</html>